Answer:
D. Durmio
Step-by-step explanation:
A: "Hizo Dormir" means he made sleep which doesn't make sense
B: "Duerme" is in present tense and they want to know what he did last night which is past tense
C: "Dormi" this is used only if you are saying it. For example, if the were asking what you did last night you would say "Dormi"
D: "Durmio" fits all the options that it should have. It is past-tense and it is from the point of another person
Hope this helps :)